1. Field of the Invention
The invention relates to a suction head for floor vacuum cleaners comprising a one-part plastic housing containing a suction channel and a top side opening for a foot switch. A bristles carrier plate is vertically movably arranged in the plastic housing and can be lowered against the action of pressure springs by actuating a foot switch inserted in the opening. A bottom plate arranged on the underside of the housing has a suction mouth adjoining a vertically aligned, box-shaped connection element of the suction channel. The suction mouth feeds into a bottom channel of the bottom plate. The plastic housing has two vertically aligned, dimensionally stable screw domes for guiding the bristles carrier plate, as well as the pressure springs. Strips of bristles and/or rubber lips are connected with the underside of the bristles carrier plate. The bristles and the lips can be retracted and extended on the underside of the plastic housing by lifting and lowering the bristles carrier plate.
2. The Prior Art
With the designs known in practical life, on which the invention is based, a bottom plate is screwed to screw domes and in this manner rigidly connected with a plastic housing.
In addition, suction heads are known with different constructional designs. For better adaptation to the floor covering, the suction heads have a movable bottom plate. With the design known from DE-A 197 17 291, the casing of the suction head has a plurality of screw domes aligned in one line, the suction domes being designed flexible, for example by means of a sheet material hinge. The bottom plate is secured on the flexible screw domes and is capable of performing swivel movements limited by stop elements. For the resetting movement, pressure springs are provided, which are preferably plugged onto and guided on the flexible screw domes. This construction requires a relatively large expenditure in time and expense to manufacture and assemble. Furthermore, the flexible screw domes are sensitive.
A suction head for a floor vacuum cleaner known from DE-A 196 08 188 has a flexibly supported bottom plate. The bottom plate is capable of performing horizontal and vertical movements that are limited by stop means. The required resetting forces are expended by pressure springs. Costly and complicated automatic assembly equipment is required for producing such suction heads in a series production with high numbers of units. Furthermore, the known design provides no possibility for extending strips of bristles on the underside for vacuum-cleaning smooth floors.
Suction heads for floor vacuum cleaners, which are referred to in practical life also as vacuum cleaner nozzles, are mass-produced articles. The invention addresses the problem of providing a suction nozzle with the structure described above that is simple in construction and has a movable bottom plate adapting itself to the floor. The goal is to keep the number of components to be assembled as small as possible. In addition, the goal is to make it possible to selectively equip the suction head also with a rigid bottom plate with no change in the design of the plastic housing.
This problem in the above-described suction heads is solved according to the invention by pivotally mounting the bottom plate both on the connection element of the suction channel and at the end side on the inner surfaces of the plastic housing. The device has a box-shaped connection element with transverse bridges that limit the suction channel laterally and whose lower edges are designed in the form of support surfaces that are rounded in the form of a curve. In addition the bottom plate is supported on the rounded, curved support surfaces of the connection element. The bottom plate is also rotatably interlocked with wall surfaces of the connection element extending parallel with the transverse bridges.
The wall surfaces of the connection element preferably contain bores that are engaged by pins shaped by molding on the bottom plate. The support surfaces rounded in the form of curves may have a side collar for fixing the bottom plate axially. The arrangement of the bottom plate on the plastic housing as defined by the invention requires no additional assembly material. The plastic housing and the bottom plate are single-piece, molded plastic components that have all the elements required for movably holding the bottom plate. Because of the design as defined by the invention, high forces can be exerted on the bottom plate without having to fear any damage to its support. The required elements for interlocking the bottom plate with the connection element, for example journal pins, can be dimensioned small and designed with adequate mobility for producing the locking connection.
In a preferred embodiment, journal pins and projections acting as bearing cups are formed by molding on the inner surfaces of the plastic housing. The journal pins engage associated bearing bores of the bottom plate. The bottom plate is vertically supported on the bearing cups. Forces acting on the bottom plate are introduced into the plastic housing via the bearing cups. The journal pins are subject to little stress and therefore can be made small. Stops are usefully formed by molding on the inner surfaces of the plastic housing to limit the angle of swivel of the bottom plate. Such stops may consist of lugs that engage an oblong hole located on the circumference of the bottom plate.
According to an advantageous embodiment of the invention, the screw domes are arranged offset sideways in relation to the axis of swivel. The pressure springs acting on the plate carrying the bristles are supported on ring disks, which are secured on the screw domes. The bottom plate is swivel-connected with the plastic housing and movable versus the screw domes. The bottom plate may be screwed to the screw domes without any change in the design of the plastic housing in order to rigidly secure the bottom plate to the suction head in a very simple way. In one embodiment of the invention comprising a rigidly secured bottom plate, the pressure springs are clamped between the bottom plate and the plate carrying the bristles.
According to the invention, the plastic housing of the suction head is a standard component of the construction that can be used without change with suction heads having either a movable or a rigidly secured bottom plate. If the suction head is to be equipped with a rigidly secured bottom plate, only minor modifications are required on the bottom plate. Such modifications consist in designing the bottom plate with additional bores associated with the screw domes, so that screws can be screwed into the screw domes through the bores. Because the plastic housing and the bottom plate are joined with each other by means of a locking connection, assembling the suction head as defined by the invention is simple.